The present invention relates to the field of hydraulic pumps. More particularly, the invention relates to an apparatus and method for arranging multiple closed circuit variable displacement pumps to support the functions of propel and harvesting on a harvesting machine.
Vehicle propulsion applications of closed circuit variable displacement pumps often require large fluid displacement capacity to support the broad range of torque and speed that is necessary for acceptable performance. Conventional harvesting machines incorporate a dedicated closed circuit variable displacement pump to support the vehicle propulsion function. Additionally, such machines usually incorporate separate closed circuit variable displacement pumps to support other machine functions, such as for example, harvesting mechanisms. It is common on such machines that the harvesting mechanisms are not being utilized when the machine is being driven at high speed conditions, such as roading the machine to and from harvesting locations. Consequently, during these high speed roading or transport conditions, the pumps that are installed on the machine to drive harvesting mechanisms are not being utilized.
It is a primary objective of this invention to utilize the available capacity of the pumps normally dedicated to support harvesting mechanism as supplementary capacity for the vehicle propulsion system during high speed roading operations.
It is a further objective of this invention to reduce the fluid displacement size requirement for the propel pump, thereby reducing the cost, physical size, and drive power requirements for this pump.
Additionally, it is an objective to improve the overall machine efficiency by reducing energy losses and horsepower requirements.
Also, it is an objective to improve the design of such machines by reducing fluid reservoir capacity requirements, and allowing for the accommodation of smaller mounting pads or drive mechanisms for propel pumps.
These and other objectives will be apparent from the drawings, as well as from the description which follows.